1. Field of the Invention
The invention relates to a hydrogen filling system and a hydrogen filling method.
2. Description of the Related Art
In recent years, a fuel cell receives attention as a power source that is excellent in operation efficiency and environmental performance. For example, a solid polymer electrolyte fuel cell generates electric power by an electrochemical reaction between hydrogen supplied to an anode electrode as fuel gas and air supplied to a cathode electrode as oxidant gas. Hydrogen gas is supplied from a hydrogen tank, filled with hydrogen gas, to the fuel cell, and a compressor is driven to supply air in the atmosphere to the fuel cell.
The hydrogen tank is filled with hydrogen gas in a hydrogen supply facility called a hydrogen station. For example, the hydrogen station includes a hydrogen gas cylinder bundle and a dispenser. The hydrogen gas cylinder bundle is a plurality of gas cylinders. The dispenser fills hydrogen, supplied from the hydrogen gas cylinder bundle, into the hydrogen tank. The dispenser is coupled to a filling port connected to the hydrogen tank, and fills hydrogen gas into the hydrogen tank by a pressure difference between the hydrogen gas cylinder bundle and the hydrogen tank.
When a hydrogen tank having a hydrogen storage alloy is filled with hydrogen, there is a technique for filling hydrogen into the hydrogen tank while cooling the hydrogen storage alloy in order to facilitate occlusion of hydrogen by the hydrogen storage alloy (for example, see Japanese Patent Application Publication No. 2004-281243 (JP-A-2004-281243). There is also a technique for filling hydrogen gas while cooling a fuel tank (for example, see Japanese Patent Application Publication No. 2007-40390 (JP-A-2007-40390)). There is also a technique for filling hydrogen; stored in a hydrogen storage source, into a hydrogen tank while cooling the hydrogen by an endothermic reaction that occurs at the time of releasing hydrogen from the hydrogen storage alloy (for example, see Japanese Patent Application Publication No. 2007-303625 (JP-A-2007-303625)).
In the existing art, in order to facilitate filling of hydrogen into the hydrogen tank, the hydrogen storage alloy or the hydrogen tank is cooled. However, when a vehicle arrives at a hydrogen station and then cooling of the hydrogen storage alloy or the hydrogen tank is started, the hydrogen storage alloy or the hydrogen tank is not sufficiently cooled immediately after the start of filling of hydrogen into the hydrogen tank. Thus, it takes time to complete filling of hydrogen into the hydrogen tank from the start of filling of hydrogen into the hydrogen tank.